1. Field of the Invention
The present invention relates to a vehicle signal lighting unit for a stop lamp, tail lamp, turn signal lamps, or the like, and more particularly to a signal lighting unit in which a sufficient depth effect and improved design can be attained by providing desired light distribution characteristics with a reflecting mirror and forming an outer lens to be almost plain.
2. Background Art
FIG. 7 shows a configuration of a similar vehicle signal lighting unit 90 based on the prior art. The vehicle signal lighting unit 90 is provided with a single light source 91 such as a filament lamp and a composite reflecting mirror 92 in which each reflecting unit 92a reflects incident light from the light source 91 horizontally and vertically to provide a proper diffusion angle. The vehicle signal lighting unit 90 is formed so that the composite reflecting mirror 92 itself provides the desired light distribution characteristics.
Accordingly, an outer lens 93 can be almost plain without any lens cut and needs not have any means for providing required light distribution characteristics. Therefore, the inside of the vehicle signal lighting unit 90 is visible through the outer lens 93 independently of whether the vehicle signal lighting unit is turned on or off. Because of this, a depth effect increases and a high-quality design is available.
When observers look into the above-mentioned vehicle signal lighting unit 90 through said outer lens 93, however, there arises such a problem that said light source 91 and a socket 91a therefor are almost directly exposed to observers, degrading aesthetics. Especially when the vehicle signal lighting unit is turned on, direct light from a high-luminance filament reaches observer's eyes. Accordingly, there is also a problem that a large contrast between light and shade on a luminescent surface decreases the visibility.
To solve the aforementioned problems, there is provided another configuration, as shown in FIG. 7, having a hood 94 provided with a lens cut 94a to diffuse the direct light. When the vehicle signal lighting unit is viewed obliquely, however, the socket 91a and other components are still exposed to observers. While the filament shape becomes unidentifiable when the light is turned on, however, there still remains a problem that the front of the hood 94 becomes too bright, causing a greater contrast between light and shade than the other locations.